Ed Balls has confessed to speeding in his West Yorkshire constituency, saying he was not only caught "bang to rights" but is now ever more convinced about the need to improve road safety after taking a speed awareness course as an alternative to points on his license.

The shadow chancellor, writing on his own blog, said he was recorded doing 56mph in a temporary 50mph zone on the M62 near his constituency in Morley, on the southern edge of the Leeds conurbation.

Amid some frantic briefing about what precisely happened, unnamed Conservative party sources assured newspapers that Osborne's driver initially parked the Land Rover in a standard bay at the Magor services on the M4 near Newport in South Wales and only moved to the disabled spot as the chancellor was inside buying a meal at McDonald's.

Osborne did not notice the car's new position when he got back in, the source insisted, adding: "George does not condone this in any way."

The chief executive of the disability charity Scope said the incident with Osborne showed the chancellor had a "toxic attitude" to the vulnerable.

Balls was somewhat more straightforward about his own misbehaviour. He wrote: "Like many local people, I was caught out by the never-ending roadworks on the M62. Pulling on to the motorway at Morley I realised too late that the speed restrictions were still in place. I was caught and bang to rights – doing 56 in a 50 mile restriction zone."

He was, Balls wrote, "going too far, too fast, you might say", a reference to his own much-used criticism of the government's economic austerity policies.

He continued: "I paid my fine and chose to attend a speed awareness course. I currently have no points on my licence and would like to keep it that way. Which is why, this week, I ended up in the Holiday Inn with 39 others. The course was very professional and actually really worthwhile. What hit home were the statistics which link speed to car deaths. At 20mph, less than 10 per cent of people will lose their lives if hit by a car. But the probability rises exponentially, going above 40 per cent at 40mph."

"Our course instructors explained that casualty rates have fallen over the past decade, as drivers have become more aware and car design has improved. The worrying thing is that this trend has started to reverse in recent years."